RE: [PATCH 00/35] Enhance memory utilization with DMEMFS

[Zengtao (B)]

> -----Original Message-----
> From: yulei.kernel@xxxxxxxxx [mailto:yulei.kernel@xxxxxxxxx]
> Sent: Thursday, October 08, 2020 3:54 PM
> To: akpm@xxxxxxxxxxxxxxxxxxxx; naoya.horiguchi@xxxxxxx;
> viro@xxxxxxxxxxxxxxxxxx; pbonzini@xxxxxxxxxx
> Cc: linux-fsdevel@xxxxxxxxxxxxxxx; kvm@xxxxxxxxxxxxxxx;
> linux-kernel@xxxxxxxxxxxxxxx; xiaoguangrong.eric@xxxxxxxxx;
> kernellwp@xxxxxxxxx; lihaiwei.kernel@xxxxxxxxx; Yulei Zhang
> Subject: [PATCH 00/35] Enhance memory utilization with DMEMFS
> 
> From: Yulei Zhang <yuleixzhang@xxxxxxxxxxx>
> 
> In current system each physical memory page is assocaited with
> a page structure which is used to track the usage of this page.
> But due to the memory usage rapidly growing in cloud environment,
> we find the resource consuming for page structure storage becomes
> highly remarkable. So is it an expense that we could spare?
> 
> This patchset introduces an idea about how to save the extra
> memory through a new virtual filesystem -- dmemfs.
> 
> Dmemfs (Direct Memory filesystem) is device memory or reserved
> memory based filesystem. This kind of memory is special as it
> is not managed by kernel and most important it is without 'struct page'.
> Therefore we can leverage the extra memory from the host system
> to support more tenants in our cloud service.
> 
> We uses a kernel boot parameter 'dmem=' to reserve the system
> memory when the host system boots up, the details can be checked
> in /Documentation/admin-guide/kernel-parameters.txt.
> 
> Theoretically for each 4k physical page it can save 64 bytes if
> we drop the 'struct page', so for guest memory with 320G it can
> save about 5G physical memory totally.

Sounds interesting, but seems your patch only support x86, have you
 considered aarch64?

Regards
Zengtao